Image processing apparatus, image processing method, and projection apparatus

ABSTRACT

The present technology relates to an image processing apparatus, an image processing method, and a projection apparatus that can improve brightness of a projected image while satisfying a safety standard for laser products. A saturation emphasis processing unit determines, in accordance with saturation of an image, a first emphasis coefficient that emphasizes luminance of the image, and converts a luminance signal of the image on the basis of the determined first emphasis coefficient. The present technology can be applied to, for example, a laser beam scanning type projection apparatus or the like that performs scanning with a laser beam as a light source.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of International PatentApplication No. PCT/JP2018/018233 filed on May 11, 2018, which claimspriority benefit of Japanese Patent Application No. JP 2017-103293 filedin the Japan Patent Office on May 25, 2017. Each of the above-referencedapplications is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present technology relates to an image processing apparatus, animage processing method, and a projection apparatus, and in particular,an image processing apparatus, an image processing method, and aprojection apparatus that can improve brightness of a projected imagewhile satisfying a safety standard for laser products.

BACKGROUND ART

Some conventional projectors, for example, scan a screen byreciprocating a laser beam sinusoidally (for example, see PatentDocument 1).

This type of projector causes a drive mirror, which reflects a laserbeam, to be scanned by resonance operation, thereby irradiating eachposition on a screen with the laser beam reflected by the drive mirror.

With this arrangement, irradiation with the laser beam causes a spot oflight, which is a spot-like light, to be projected on each position onthe screen. In other words, an image is projected on the screen, with aplurality of spots of light each serving as a pixel.

CITATION LIST Patent Document

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2003-021800

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Such a projector that performs scanning with a laser beam is subject toa restriction on laser power in order to satisfy the safety standard forlaser products. Due to the restriction on laser power, brightness of aprojected image is also restricted.

The present technology has been made in view of such a situation, and isintended to improve brightness of a projected image while satisfying thesafety standard for laser products.

Solutions to Problems

An image processing apparatus according to one aspect of the presenttechnology includes a saturation emphasis processing unit thatdetermines, in accordance with saturation of an image, a first emphasiscoefficient that emphasizes luminance of the image, and converts aluminance signal of the image on the basis of the determined firstemphasis coefficient.

In an image processing method according to one aspect of the presenttechnology, an image processing apparatus determines, in accordance withsaturation of an image, an emphasis coefficient that emphasizesluminance of the image, and converts a luminance signal of the image onthe basis of the determined emphasis coefficient.

A projection apparatus according to one aspect of the present technologyincludes a saturation emphasis processing unit that determines, inaccordance with saturation of an input image, an emphasis coefficientthat emphasizes luminance of the image, and converts a luminance signalof the image on the basis of the determined emphasis coefficient, alaser light source unit that outputs a laser beam in accordance with apixel signal of the image obtained by converting the luminance signal,and a scanning unit that reflects the laser beam and performs scanningwith the laser beam in a horizontal direction and a vertical direction.

In one aspect of the present technology, in accordance with saturationof an image, a first emphasis coefficient that emphasizes luminance ofthe image is determined, and a luminance signal of the image isconverted on the basis of the determined first emphasis coefficient.

Note that the image processing apparatus according to one aspect of thepresent technology can be achieved by causing a computer to execute aprogram.

Furthermore, in order to achieve the image processing apparatusaccording to one aspect of the present technology, a program to beexecuted by a computer can be provided by being transmitted via atransmission medium or being recorded on a recording medium.

The image processing apparatus may be an independent apparatus, or maybe an internal block constituting one apparatus.

Effects of the Invention

According to one aspect of the present technology, it is possible toimprove brightness of a projected image while satisfying the safetystandard for laser products.

Note that the effects described here are not necessarily restrictive,and the effects of the invention may be any of the effects described inthe present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration example of aprojection apparatus to which the present technology is applied.

FIG. 2 is a diagram illustrating in more detail a configuration of alaser light source unit.

FIG. 3 is a diagram for describing raster scanning.

FIG. 4 is a block diagram for describing a general flow of signalprocessing.

FIG. 5 is a diagram for describing a relationship between a scanningspeed and laser power.

FIG. 6 is a diagram for describing a laser safety standard.

FIG. 7 is a diagram for describing laser power in a case where an actualimage is projected.

FIG. 8 is a block diagram for describing a flow of signal processing inthe projection apparatus in FIG. 1 .

FIG. 9 is a block diagram illustrating a detailed configuration of anemphasis processing unit.

FIG. 10 is a diagram for describing a relationship between saturationand U and V signals.

FIG. 11 is a diagram for describing a relationship between saturationand laser power.

FIGS. 12A and 12B are diagrams for describing a correspondencerelationship between a variable ΔUV and an emphasis coefficient Coeff1.

FIGS. 13A and 13B are diagrams for describing a correspondencerelationship between a margin Mg and an emphasis coefficient Coeff1.

FIG. 14 is a diagram for describing processing performed by a saturationemphasis processing unit.

FIGS. 15A and 15B are diagrams for describing a relationship between anarea of a projection image and an eye.

FIG. 16 is a diagram for describing a correspondence relationshipbetween a total laser power value Area_(avgTTL) and an emphasiscoefficient Coeff2.

FIG. 17 is a diagram for describing processing performed by an areaemphasis processing unit.

FIG. 18 is a flowchart for describing emphasis processing.

FIG. 19 is a flowchart for describing saturation emphasis processing.

FIG. 20 is a flowchart for describing saturation emphasis processing.

FIG. 21 is a flowchart for describing area emphasis processing.

FIG. 22 is a block diagram illustrating another configuration example ofa projection apparatus to which the present technology is applied.

FIG. 23 is a block diagram illustrating a configuration example of acomputer to which the present technology is applied.

FIG. 24 is a block diagram illustrating a configuration example ofelectronic equipment to which the present technology is applied.

MODE FOR CARRYING OUT THE INVENTION

A mode for carrying out the present technology (hereinafter referred toas an “embodiment”) will be described below. Note that the descriptionwill be made in the order below.

1. Configuration example of projection apparatus

2. Raster scanning

3. General flow of signal processing

4. Flow of signal processing in projection apparatus 1

5. Detailed configuration of emphasis processing unit 61

6. Details of saturation emphasis processing unit 71

7. Details of area emphasis processing unit 72

8. Flowchart

9. Other configuration examples of projection apparatus

10. Configuration example of computer

11. Example of application to electronic equipment as projection module

<1. Configuration Example of Projection Apparatus>

FIG. 1 is a block diagram illustrating a configuration example of aprojection apparatus to which the present technology is applied.

This projection apparatus 1 is a laser beam scanning type projectionapparatus (projector) that projects a projection image 2 a onto a screen2 by performing scanning with a laser beam as a light source. Note thatthe projection image 2 a can be projected not only onto the screen 2 butalso onto a wall surface, a flat surface of a predetermined object, orthe like.

The projection apparatus 1 includes a controller 21, a laser driver 22,a mirror driver 23, laser light source units 24R, 24G, and 24B, a mirror25, dichroic mirrors 26-1 and 26-2, a drive mirror 27, and an opticallens 28.

The controller 21 is supplied with image signals of the projection image2 a to be projected on the screen 2 as input image signals from anotherapparatus, for example, a personal computer.

The controller 21 generates pixel data for each color (red, green, andblue) of each pixel constituting the projection image 2 a on the basisof input image signals supplied from another apparatus, and supplies thelaser driver 22 with the pixel data in synchronization with a mirrorsynchronization signal acquired from the mirror driver 23. Note that themirror synchronization signal is a signal for driving the mirror driver23 in synchronization with the input image signals.

On the basis of the pixel data for each color supplied from thecontroller 21, the laser driver 22 generates drive signals in accordancewith pixel values for each pixel of the projection image 2 a, andsupplies the drive signals to the laser light source units 24R, 24G, and24B. Specifically, the laser driver 22 supplies a drive signal inaccordance with red pixel data to the laser light source unit 24R,supplies a drive signal in accordance with green pixel data to the laserlight source unit 24G, and supplies a drive signal in accordance withblue pixel data to the laser light source unit 24B.

To scan the screen 2 with a laser beam in a horizontal direction (leftand right direction in the figure) and a vertical direction (up and downdirection in the figure), the mirror driver 23 generates a horizontalscan signal and a vertical scan signal based on a resonance frequency ofthe drive mirror 27, and supplies the horizontal scan signal and thevertical scan signal to the drive mirror 27. Furthermore, the mirrordriver 23 has a light receiving unit (not illustrated) that detects apart of the laser beam reflected by the drive mirror 27. Then, themirror driver 23 adjusts the horizontal scan signal and the verticalscan signal on the basis of a result of detection by the light receivingunit, and feeds back, to the controller 21, a detection signal inaccordance with the result of detection by the light receiving unit.

The laser light source units 24R, 24G, and 24B output laser beams ofcorresponding colors (light wavelengths) in accordance with the drivesignals supplied from the laser driver 22. Specifically, the laser lightsource unit 24R outputs a red laser beam with a power in accordance withthe red pixel data. The laser light source unit 24G outputs a greenlaser beam with a power in accordance with the green pixel data. Thelaser light source unit 24B outputs a blue laser beam with a power inaccordance with the blue pixel data.

Note that the laser light source units 24R, 24G, and 24B are hereinaftercollectively referred to simply as the “laser light source unit 24” in acase where it is not necessary to distinguish the laser light sourceunits 24R, 24G, and 24B.

The mirror 25 reflects the red laser beam output from the laser lightsource unit 24R. The dichroic mirror 26-1 reflects the green laser beamoutput from the laser light source unit 24G and transmits the red laserbeam reflected by the mirror 25. The dichroic mirror 26-2 reflects theblue laser beam output from the laser light source unit 24B, andtransmits the red laser beam reflected by the mirror 25 and the greenlaser beam reflected by the dichroic mirror 26-1. Note that the mirror25 and the dichroic mirrors 26-1 and 26-2 are combined and disposed suchthat optical axes of the laser beams output from the laser light sourceunits 24R, 24G, and 24B are coaxial.

The drive mirror 27 is, for example, a minute mirror formed by a microelectro mechanical system (MEMS), and is driven in accordance with thehorizontal scan signal and the vertical scan signal supplied from themirror driver 23. In other words, for example, the drive mirror 27reflects the laser beam output from each of the laser light source units24R, 24G, and 24B and performs scanning with the laser beam across thescreen 2 in the horizontal direction and the vertical direction.

The optical lens 28 is disposed on an optical path of the laser beamtraveling from the drive mirror 27 to the screen 2, and corrects theoptical path of the laser beam.

Note that the projection apparatus 1 can adopt a configuration in whichthe laser driver 22 and the mirror driver 23 are integrated into thecontroller 21. Furthermore, the projection apparatus 1 may be configuredsuch that the optical lens 28 is not disposed on the optical path of thelaser beam.

FIG. 2 is a diagram illustrating in more detail a configuration of thelaser light source units 24R, 24G, and 24B.

The laser light source units 24R, 24G, and 24B respectively includelaser beam generation units 24Ra, 24Ga, and 24Ba and collimator lenses24Rb, 24Gb, and 24Bb, for wavelengths of R (red), G (green), and B(blue) respectively. In other words, the laser light source units 24R,24G, and 24B respectively have the laser beam generation units 24Ra,24Ga, and 24Ba that generate laser beams of wavelengths specific to therespective colors, and the collimator lenses 24Rb, 24Gb, and 24Bb thatcollimate and output the laser beams of the respective wavelengths. Notethat the laser beam generation units 24Ra, 24Ga, and 24Ba and thecollimator lenses 24Rb, 24Gb, and 24Bb are collectively referred tosimply as the “laser beam generation unit 24 a” and the “collimator lens24 b” respectively, in a case where it is not necessary to particularlydistinguish the respective colors (wavelengths).

The laser beam generation unit 24Ra emits a red laser beam on the basisof a drive signal (Video Data Current Red) in accordance with the redpixel data. The collimator lens 24Rb appropriately adjusts an emissiondirection of the red laser beam emitted from the laser beam generationunit 24Ra, and then the red laser beam is reflected by the mirror 25 andenters the dichroic mirror 26-1.

The laser beam generation unit 24Ga emits a green laser beam on thebasis of a drive signal (Video Data Current Green) in accordance withthe green pixel data. The collimator lens 24Gb appropriately adjusts anemission direction of the green laser beam emitted from the laser beamgeneration unit 24Ga, and then the green laser beam is reflected by thedichroic mirror 26-1 and enters the dichroic mirror 26-2. Furthermore,the dichroic mirror 26-1 transmits the red laser beam that enters fromthe mirror 25, thereby allowing the red laser beam to enter the dichroicmirror 26-2.

The laser beam generation unit 24Ba emits a blue laser beam on the basisof a drive signal (Video Data Current Blue) in accordance with the bluepixel data. The collimator lens 24Bb appropriately adjusts an emissiondirection of the blue laser beam radiated from the laser beam generationunit 24Ba, and then the blue laser beam is reflected by the dichroicmirror 26-2 and enters the drive mirror 27. Furthermore, the dichroicmirror 26-2 transmits the red and green laser beams that enter from thedichroic mirror 26-1, thereby allowing the red and green laser beams toenter the drive mirror 27. As a result, the red, green, and blue (R, G,and B) laser beams from the dichroic mirror 26-2 enter the drive mirror27 as a multiplexed beam.

The projection apparatus 1 drives the drive mirror 27 to performscanning with the red, green, and blue laser beams, thereby projecting atwo-dimensional projection image 2 a on the screen 2. Examples of thelaser beam scanning method by using the drive mirror 27 includes, forexample, a method called “raster scanning” and a method called“Lissajous scanning”. The projection apparatus 1 adopts, for example,raster scanning.

<2. Raster Scanning>

Raster scanning will be described with reference to FIG. 3 .

In FIG. 3 , a scanning locus of the laser beam in raster scanning isillustrated on the projection image 2 a, a horizontal scan signal H-Scanis illustrated below the projection image 2 a, and a vertical scansignal V-Scan is illustrated to the left of the projection image 2 a.

The horizontal scan signal H-Scan is, for example, a sinusoidal signaloscillating at about 20 kHz in accordance with the resonance frequencyof the drive mirror 27, and a frequency of the horizontal scan signalH-Scan is half a horizontal synchronization frequency of the projectionimage 2 a. The vertical scan signal V-Scan is, for example, a signalhaving a sawtooth waveform and oscillating at 60 Hz, which is afrequency in accordance with a frame period of the projection image 2 a.

Note that the laser beam does not emit light in the scanning locus inthe vicinity of both edges of the horizontal scan signal H-Scan. Thisallows turn portions of the scanning locus to be excluded fromprojection of the projection image 2 a. Furthermore, the laser beam doesnot emit light in a section where the vertical scan signal V-Scan showsa waveform that rises substantially vertically, that is, in a flybacksection in which the scanning locus of the laser beam shows a steepslope from a bottom edge (end position of the scanning) to a top edge(start position of the next scanning).

Driving the drive mirror 27 in accordance with the horizontal scansignal H-Scan and the vertical scan signal V-Scan as described abovecauses scanning with the laser beam to be performed along a scanninglocus as illustrated on the projection image 2 a. As illustrated,scanning with the laser beam is performed in both directions. Thescanning direction of the laser beam is reversed in every horizontalscanning line, and it is therefore necessary to rearrange order of inputimage signals or change a data access direction for the input imagesignals in every scanning line.

Furthermore, as illustrated below the horizontal scan signal H-Scan inFIG. 3 , a scanning speed of the laser beam in the horizontal directionincreases at the center of the projection image 2 a and decreases in thevicinity of edges of the projection image 2 a. The scanning speed of thelaser beam in the vertical direction is fixed regardless of the positionin the projection image 2 a. Note that, for the sake of simplicity, theentire projection image 2 a may be referred to as the “screen” in thedescription below.

<3. General Flow of Signal Processing>

FIG. 4 is a block diagram illustrating a general flow of signalprocessing in which input image signals are converted into drive signalsto be input to the laser light source unit 24.

Input image signals supplied from another apparatus are converted intodrive signals by undergoing predetermined processing in each of an imagequality adjustment processing unit 41, a pixel signal conversion unit42, and a drive signal conversion unit 43, and are supplied to the laserlight source unit 24.

The image quality adjustment processing unit 41 executes, on the inputimage signals, general image quality adjustment processing such ascontrast adjustment and sharpness adjustment, and supplies the processedimage signals to the pixel signal conversion unit 42.

The input image signals are supplied, for example, as image signals in aYUV format. A signal in the YUV format is represented by a luminancesignal Y and Cb(U) and Cr(V) components, the components being twocolor-difference signals (Cb and Cr signals). The luminance signal Y hasa value in a range of 0 to 1, and the Cb and Cr signals have values in arange of −0.5 to +0.5. The Cb and Cr signals are also convenientlyreferred to as the “U and V signals”.

The pixel signal conversion unit 42 converts the image signals suppliedfrom the image quality adjustment processing unit 41 into pixel signalsfor each pixel constituting the screen in accordance with a rasterscanning trajectory. More specifically, the pixel signal conversion unit42 converts the image signals in the YUV format supplied from the imagequality adjustment processing unit 41 into image signals in an RGBformat, thereby converting the image signals into pixel signals (pixeldata), one for each of R, G, and B of each pixel constituting the screenin accordance with the raster scanning trajectory.

The drive signal conversion unit 43 converts the pixel signals suppliedfrom the pixel signal conversion unit 42 into drive signals for each ofR, G, and B, and supplies the drive signals to the laser light sourceunit 24.

When the pixel signal conversion unit 42 converts the image signals intopixel signals for each of R, G, and B in accordance with the rasterscanning trajectory, laser power adjustment in accordance with thescanning speed is also performed.

In other words, as illustrated in a graph on the left side of FIG. 5 ,the scanning speed of the laser beam in the horizontal directionincreases at the center of the screen and decreases in the vicinity ofedges of the screen. This difference in scanning speed causesaccumulated power to vary in accordance with the position in the screenin a case where the power remains the same during scanning in thehorizontal direction. That is to say, in a case where the power remainsthe same during horizontal scanning, the laser beam enters a human eyefor a longer period of time in the vicinity of the screen edges wherethe scanning speed is low, resulting in more power of laser that entersthe eye.

Thus, in order to satisfy a laser safety standard, as illustrated in agraph on the right side of FIG. 5 , it is necessary to ensure safety byreducing the laser power in the vicinity of the screen edges where thescanning speed is low.

The laser safety standard imposes constraints on several conditions suchas an accumulated power per unit time of a laser beam that enters ahuman eye and an instantaneous power so that safety can be maintainedeven when a collimated and highly focused laser beam enters a human eyeas illustrated in FIG. 6 .

The laser power becomes the largest in an image in which each of Rlight, G light, and B light is emitted at 100%, that is, in a whiteimage. Accordingly, as illustrated in the graph on the right side ofFIG. 5 , the laser power is controlled within a laser safety standardlimit value indicated by a broken line even in a case where the laserlight source unit 24 emits white light with R, G, and B at 100%. Adifference between the laser safety standard limit value and the powerwhen R light, G light, and B light are emitted at 100% corresponds to amargin set in the projection apparatus 1. The laser safety standardserves as a restriction for projecting a bright image while constrainingthe power of a laser light source that can output a laser beam as aprojection apparatus.

On the other hand, in general, an image actually displayed by aprojection apparatus often includes image signals (pixel signals) thatcause brightness of about 30% just like a curve illustrated as an actualimage in FIG. 7 , and the projection apparatus operates at a powersufficiently smaller than the laser safety standard limit value.

Thus, the projection apparatus 1 analyzes a configuration of an image,specifically, hue of the image such as a single color or a pure color,and increases the laser power within the laser safety standard limitvalue in accordance with the analyzed hue of the image, therebyimproving brightness of the image to be projected.

<4. Flow of Signal Processing in Projection Apparatus 1>

FIG. 8 is a block diagram illustrating a flow of signal processing inwhich the projection apparatus 1 converts input image signals into drivesignals.

Comparing the flow of processing performed by the projection apparatus 1illustrated in FIG. 8 with the flow of general processing illustrated inFIG. 4 , an emphasis processing unit 61 is newly disposed between theimage quality adjustment processing unit 41 and the pixel signalconversion unit 42. Processing performed by the image quality adjustmentprocessing unit 41, the pixel signal conversion unit 42, and the drivesignal conversion unit 43 is similar to the processing described withreference to FIG. 4 , and therefore the description thereof is omitted.

The emphasis processing unit 61 executes emphasis processing on imagesignals supplied from the image quality adjustment processing unit 41,in which a configuration of an image, specifically, hue of the imagesuch as a single color or a pure color, is analyzed and the imagesignals are emphasized in accordance with the analyzed hue of the image.The emphasis processing unit 61 supplies the emphasized image signals tothe pixel signal conversion unit 42.

The image quality adjustment processing unit 41, the pixel signalconversion unit 42, and the emphasis processing unit 61 in FIG. 8correspond to a processing block executed by the controller 21 in FIG. 1, and the drive signal conversion unit 43 in FIG. 8 corresponds to aprocessing block executed by the laser driver 22 in FIG. 1 .

<5. Detailed Configuration of Emphasis Processing Unit 61>

FIG. 9 illustrates a detailed configuration of the emphasis processingunit 61.

The emphasis processing unit 61 includes a saturation emphasisprocessing unit 71 and an area emphasis processing unit 72.

The saturation emphasis processing unit 71 is supplied with an imagesignal in the YUV format that has undergone general image qualityadjustment processing such as contrast adjustment and sharpnessadjustment in the image quality adjustment processing unit 41.

In accordance with saturation of an image supplied from the imagequality adjustment processing unit 41, the saturation emphasisprocessing unit 71 determines an emphasis coefficient Coeff1 (firstemphasis coefficient Coeff1) that emphasizes luminance of the image.Then, the saturation emphasis processing unit 71 emphasizes (converts) aluminance signal Y of the image on the basis of the determined emphasiscoefficient Coeff1. Specifically, on the basis of the luminance signal Yof the image signal in the YUV format supplied from the image qualityadjustment processing unit 41, the saturation emphasis processing unit71 computes a luminance signal Y′=Coeff1*Y by using the determinedemphasis coefficient Coeff1 to calculate the emphasized luminance signalY′, and outputs the luminance signal Y′ to the area emphasis processingunit 72.

The area emphasis processing unit 72 divides an image supplied from thesaturation emphasis processing unit 71 into a plurality of areas, anddetermines an emphasis coefficient Coeff2 (second emphasis coefficientCoeff2) that emphasizes luminance of the image for each area. Then, thearea emphasis processing unit 72 emphasizes (converts) the luminancesignal Y′ on the basis of the determined emphasis coefficient Coeff2.Specifically, on the basis of the luminance signal Y′ of the imagesignal in the YUV format supplied from the saturation emphasisprocessing unit 71, the area emphasis processing unit 72 computes aluminance signal Y″=Coeff2*Y′ by using the determined emphasiscoefficient Coeff2 to calculate the emphasized luminance signal Y″, andoutputs the luminance signal Y″ to the pixel signal conversion unit 42.

The pixel signal conversion unit 42 converts the luminance signal Y″ andthe two color-difference signals (Cb and Cr signals) into R, G, and Bpixel signals, the luminance signal Y″ being obtained by emphasizing theluminance signal Y by the saturation emphasis processing unit 71 and thearea emphasis processing unit 72.

Details of processing performed by the saturation emphasis processingunit 71 and the area emphasis processing unit 72 will be furtherdescribed below.

<6. Details of Saturation Emphasis Processing Unit 71>

First, details of the processing performed by the saturation emphasisprocessing unit 71 will be described.

The saturation emphasis processing unit 71 analyzes saturation of theimage signals supplied from the image quality adjustment processing unit41 for each pixel, and uses the predetermined emphasis coefficientCoeff1 to emphasize the luminance signal Y of a highly saturated pixel.

Here, a highly saturated pixel means a pixel having hue that is notwhite but close to a pure color or a single color such as red, green, orblue. In UV color space, the more the values of the U and V signals areaway from zero, the more the hue becomes highly saturated as illustratedin FIG. 10 .

In a case of a highly saturated pixel, not all of red, green, and blue(R, G, and B) lasers emit light at nearly 100%. At least one of red,green, or blue laser operates at a lower power.

For example, as illustrated in FIG. 11 , in a case where the red andgreen (R and G) lasers emit light at 100% but the blue laser emits lightat 0%, the power when R light and G light are emitted at 100%, which isthe power of the output lasers, is sufficiently lower than the powerwhen R light, G light, and B light are emitted at 100%. With the bluelaser not emitting light, there is room to allow the red and green (Rand G) lasers to emit light with a power of 100% or more.

In this way, the saturation emphasis processing unit 71 analyzessaturation of the image signals for each pixel, and converts theluminance signal Y into the emphasized luminance signal Y′ for pixelshaving hue close to a pure color or a single color such as red, green,or blue.

More specifically, the saturation emphasis processing unit 71 sets eachpixel constituting the screen as a pixel of interest, detects absolutevalues of the U and V signals, which are color-difference components ofthe pixel of interest, and determines either the absolute value of the Usignal or the absolute value of the V signal, whichever is larger, as avariable ΔUV for calculating the emphasis coefficient Coeff1.

Then, the saturation emphasis processing unit 71 substitutes thedetermined variable ΔUV into a function ƒ(ΔUV) that defines acorrespondence relationship between the variable ΔUV and the emphasiscoefficient Coeff1, to determine (calculate) the emphasis coefficientCoeff1 in accordance with saturation of the pixel of interest. Then, thesaturation emphasis processing unit 71 multiplies the luminance signal Yof the pixel of interest by the determined emphasis coefficient Coeff1to calculate the emphasized luminance signal Y′.

FIG. 12A illustrates an example of the function ƒ(ΔUV) that defines thecorrespondence relationship between the variable ΔUV and the emphasiscoefficient Coeff1.

Since the U and V signals both have values in a range of −0.5 to +0.5,the absolute values of the U and V signals are in a range of 0 to 0.5.In the function ƒ(ΔUV), the emphasis coefficient Coeff1 increases as thevariable ΔUV is closer to 0.5. When the variable ΔUV is 0.5, theemphasis coefficient Coeff1 is 2.0. In FIG. 12A, the emphasiscoefficient Coeff1 equivalent to the power when R light, G light, and Blight are emitted at 100% is, for example, 3.0. Since the functionƒ(ΔUV) is defined such that the emphasis coefficient Coeff1 is set in arange that does not exceed 2.0, which is smaller than 3.0, the luminancesignal Y is emphasized within the laser safety standard limit value.

FIG. 12B illustrates a concept of the emphasis coefficient Coeff1 inaccordance with the variable ΔUV, and indicates that the emphasiscoefficient Coeff1 is set larger as a distance from the origin (center)in the UV color space increases.

Note that, as can be seen from FIGS. 10 and 11 , the emphasiscoefficient Coeff1 can be set to a larger value as the hue is closer toa single color. Thus, the saturation emphasis processing unit 71 canalso adopt a method in which red, green, and blue (R, G, and B) colorsare analyzed in more detail and the emphasis coefficient Coeff1 isdetermined on the basis of R, G, and B values of the image.

Specifically, first, the saturation emphasis processing unit 71 convertsan image signal in the YUV format into an image signal in the RGB format(hereinafter also referred to as “R, G, and B signals”). For example,according to the ITU-R BT.601 and ITU-R BT.709 standards, an imagesignal in the YUV format can be converted into an image signal in theRGB format by using conversion equations described below.R=Y+1.402*CrG=Y−0.344136*Cb−0.714136*CrB=Y+1.772*Cb

Next, the saturation emphasis processing unit 71 normalizes the imagesignal in the RGB format with maxRGB, which is a maximum value amongvalues that R, G, and B signals may have. In other words, the saturationemphasis processing unit 71 sets each pixel constituting the screen as apixel of interest, and uses the equations described below to calculateRnrm, Gnrm, and Bnrm, which are normalized R, B, and G signals obtainedon the basis of the R, B, and G signals of the pixel of interest.Rnrm=R/maxRGBGnrm=G/maxRGBBnrm=B/maxRGB

Here, for example, in a case where the image signal in the RGB format isa signal represented by 8 bits, maxRGB, which is the maximum value amongthe values that the R, G, and B signals may have, is 255.

Then, as expressed by the equation below, the saturation emphasisprocessing unit 71 determines (calculates) the margin Mg by multiplyingRnrm, Gnrm, and Bnrm, which are the normalized R, B, and G signals ofthe pixel of interest, by power coefficients Cr, Cg, and Cb for R, G,and B respectively, and then subtracting the obtained values from 1. Thepower coefficients Cr, Cg, and Cb respectively correspond to powerratios of the laser light source units 24R, 24G, and 24B when the laserlight source unit 24 displays white as an image.Mg=1−(Rnrm*Cr+Gnrm*Cg+Bnrm*Cb)

Finally, the saturation emphasis processing unit 71 determines(calculates) the emphasis coefficient Coeff1 in accordance with thesaturation of the pixel of interest by substituting the determinedmargin Mg into a function ƒ(Mg) that defines a correspondencerelationship between the margin Mg and the emphasis coefficient Coeff1.Then, the saturation emphasis processing unit 71 multiplies theluminance signal Y of the pixel of interest by the determined emphasiscoefficient Coeff1 to calculate the emphasized luminance signal Y′.

FIG. 13A illustrates an example of the function ƒ(Mg) that defines thecorrespondence relationship between the margin Mg and the emphasiscoefficient Coeff1.

In the function ƒ(Mg), the emphasis coefficient Coeff1 increases as themargin Mg, which is a value computed by using Rnrm, Gnrm, and Bnrm andthe power coefficients Cr, Cg, and Cb, increases. The emphasiscoefficient Coeff1 equivalent to the power when R light, G light, and Blight are emitted at 100% is, for example, 3.0. Since the function ƒ(Mg)is defined such that the emphasis coefficient Coeff1 is set in a rangethat does not exceed 2.0, which is smaller than 3.0, the luminancesignal Y is emphasized within the laser safety standard limit value.

FIG. 13B illustrates a concept of the emphasis coefficient Coeff1 inaccordance with the margin Mg, and indicates that the emphasiscoefficient Coeff1 is set larger as a distance from the origin (center)in the UV color space increases.

The saturation emphasis processing unit 71 executes either emphasisprocessing based on U and V values, in which the emphasis coefficientCoeff1 in accordance with the variable ΔUV is determined and theluminance signal Y′ is calculated, or emphasis processing based on theR, G, and B values, in which the emphasis coefficient Coeff1 inaccordance with the margin Mg computed from the R, G, and B values isdetermined and the luminance signal Y′ is calculated. The saturationemphasis processing unit 71 subsequently outputs the calculatedluminance signal Y′.

Note that whether to execute the emphasis processing based on the U andV values or the emphasis processing based on the R, G, and B values canbe determined, for example, on a setting screen or the like before aninput image signal is supplied.

As described above, the processing performed by the saturation emphasisprocessing unit 71 analyzes the color-difference of the input imagesignals for each pixel. This allows at least one of R light, G light, orB light to be emitted at more than 100% of a normal time as illustratedin FIG. 14 . With this arrangement, it is possible to improve brightnessof a projected image while satisfying the safety standard for laserproducts.

<7. Details of Area Emphasis Processing Unit 72>

Next, details of the processing performed by the area emphasisprocessing unit 72 will be described.

There are cases where the projection image 2 a projected onto the screen2 by the projection apparatus 1 is an image in which light is brightlyemitted only in small areas. An image in which light is brightly emittedonly in small areas is, for example, an image of the universe, a starrysky, or the like. In such an image, the areas in which each of R light,G light, and B light is emitted at 100% are extremely narrow, and thereis room to increase the power of emitting light because, in a case wherea laser safety standard restricts a total accumulated value for a humaneye, the total accumulated value of such an image is sufficiently lowerthan the laser safety standard.

Thus, the area emphasis processing unit 72 divides a screen into aplurality of areas, determines an emphasis coefficient Coeff2 of eacharea in consideration of an accumulated power value for a human eye, anduses the determined emphasis coefficient Coeff2 to convert a luminancesignal Y′ into a luminance signal Y″.

There is no restriction on the number of the plurality of areas intowhich the screen is divided, and the screen can be divided into anoptional number. However, taking into consideration that an eye isdisposed randomly in a projection area, the number of areas into whichthe screen is divided is set such that the size of each of the pluralityof divided areas is smaller than the size of a pupil of a human eye. Thenumber of areas into which the screen is divided can be determined by auser on the setting screen or the like.

For example, as illustrated in FIG. 15A, in a case where an aspect ratioof the projection image 2 a is 16:9, a distance from the projectionapparatus 1 to the screen 2 is 100 mm, and a throw ratio (=projectiondistance/horizontal angle of view), which is a ratio between aprojection distance and a horizontal angle of view, is 1.0, the angle ofview of the projection image 2 a is 100 mm×56.3 mm, and a human eye,which is about 7 mm in diameter, corresponds to 7% of the horizontalangle of view in size and 12.4% of a vertical angle of view in size.

Then, in a case where the size of each of the divided areas and the sizeof a pupil of a human eye are in a relationship as illustrated in FIG.15B, areas 1 to 9 constituting nine (3×3) areas have an area size largerthan the size of a pupil of a human eye.

In a case of determining the emphasis coefficient Coeff2 of apredetermined area of interest among the plurality of divided areas, thearea emphasis processing unit 72 calculates a total laser power valueArea_(avgTTL) in an area of a size larger than the size of a pupil of ahuman eye, the area being obtained by combining the area of interest andits neighboring areas.

For example, in a case of determining the emphasis coefficient Coeff2 inthe area 5 with the area 5 as the area of interest, the area emphasisprocessing unit 72 uses the Equation (1) below to calculate the totallaser power value Area_(avgTTL) in the entire nine (3×3) areas centeredon the area 5.

$\begin{matrix}\left\lbrack {{Mathematical}{Formula}1} \right\rbrack &  \\{{Area}_{avgTTL} = {{Area}_{{avg}1} + {Area}_{{avg}2} + {Area}_{{avg}4} + \cdots + {Area}_{{avg}9}}} & (1)\end{matrix}$ $\begin{matrix}{{Area}_{avg} = \frac{\left( {{C_{r}{\sum R}} + {C_{g}{\sum G}} + {C_{b}{\sum B}}} \right)}{{Area}_{ttl\_ pixel}}} & (2)\end{matrix}$

According to Equation (1), the total laser power value (totalaccumulated value) Area_(avgTTL) of the entire nine areas is obtained byadding average laser power values Area_(avg1) to Area_(avg9) in theareas 1 to 9.

Each of the average laser power values Area_(avg1) to Area_(avg9) in theareas 1 to 9 in Equation (1) is calculated by using Equation (2).Equation (2) represents that each of the average laser power values isobtained by respectively multiplying sums of signals of all pixels inthe area for R, G, and B respectively by the power coefficients Cr, Cg,and Cb for R, G, and B respectively, adding all the multiplicationresults, and dividing the total by the number of pixels Area_(tt1_pixel)in the area.

As described above, the area for calculating the accumulated power valueis determined in relation to the size of a pupil of a human eye (about 7mm in diameter).

The area emphasis processing unit 72 determines whether the total laserpower value Area_(avgTTL) in the 3×3 neighboring areas centered on thearea of interest (area 5) calculated by using Equation (1) is smallerthan a threshold Th determined on the basis of the laser safetystandard.

In a case where it is determined that the total laser power valueArea_(avgTTL) in the 3×3 neighboring areas centered on the area ofinterest is smaller than the threshold Th, the area emphasis processingunit 72 determines the emphasis coefficient Coeff2 in accordance withthe accumulated power value in the area of interest by substituting thecalculated total laser power value Area_(avgTTL) into a functiong(Area_(avgTTL)) that defines a correspondence relationship between thetotal laser power value Area_(avgTTL) and the emphasis coefficientCoeff2 as illustrated in FIG. 16 . Then, the area emphasis processingunit 72 multiplies the luminance signal Y′ of each pixel in the area ofinterest by the determined emphasis coefficient Coeff2 to calculate theemphasized luminance signal Y″ of each pixel in the area of interest.

A function g_(max)(Area_(avgTTL)) indicated by a broken line in FIG. 16represents upper limit values of the emphasis coefficient Coeff2 withinthe laser safety standard. Accordingly, the function g(Area_(avgTTL))that defines the correspondence relationship between the total laserpower value Area_(avgTTL) and the emphasis coefficient Coeff2 is setsuch that the luminance signal Y′ is emphasized within the laser safetystandard limit value.

As described above, the processing performed by the area emphasisprocessing unit 72 calculates an accumulated laser power valuecorresponding to the input image signals for each area of apredetermined size. This allows at least one of R light, G light, or Blight to be emitted at more than 100% of a normal time as illustrated inFIG. 17 . With this arrangement, it is possible to improve brightness ofa projected image while satisfying the safety standard for laserproducts.

<8. Flowchart>

Next, emphasis processing executed by the emphasis processing unit 61 ofthe projection apparatus 1 will be described with reference to aflowchart in FIG. 18 . This processing is started, for example, when animage signal in the YUV format is supplied to (the saturation emphasisprocessing unit 71 of) the emphasis processing unit 61.

First, in step S1, the saturation emphasis processing unit 71 executessaturation emphasis processing to emphasize a luminance signal Y byusing the emphasis coefficient Coeff1 in accordance with saturation ofan image supplied from the image quality adjustment processing unit 41.Details of the saturation emphasis processing will be described laterwith reference to FIGS. 19 and 20 . The saturation emphasis processingconverts the luminance signal Y of each pixel of the image supplied fromthe image quality adjustment processing unit 41 into a luminance signalY′=Coeff1*Y, and outputs the luminance signal Y′ to the area emphasisprocessing unit 72.

In step S2, the area emphasis processing unit 72 divides the imagesupplied from the saturation emphasis processing unit 71 into aplurality of areas, and executes area emphasis processing to emphasizethe luminance signal Y′ by using the emphasis coefficient Coeff2 foreach area. Details of the area emphasis processing will be describedlater with reference to FIG. 21 . The area emphasis processing convertsthe luminance signal Y′ of each pixel of the image supplied from thesaturation emphasis processing unit 71 into a luminance signalY″=Coeff2*Y′, and outputs the luminance signal Y″ to the pixel signalconversion unit 42.

FIG. 19 is a flowchart for describing details of the saturation emphasisprocessing in step S1, and is a flowchart of the saturation emphasisprocessing in a case where the emphasis coefficient Coeff1 is calculatedon the basis of U and V values of a pixel.

In the flowchart in FIG. 19 , first, in step S21, the saturationemphasis processing unit 71 sets a predetermined pixel of the imagesupplied from the image quality adjustment processing unit 41 as a pixelof interest.

In step S22, the saturation emphasis processing unit 71 detects absolutevalues of the U and V signals of the pixel of interest, and determineseither the absolute value of the U signal or the absolute value of the Vsignal, whichever is larger, as a variable ΔUV for calculating theemphasis coefficient Coeff1.

In step S23, the saturation emphasis processing unit 71 substitutes thedetermined variable ΔUV into the function ƒ(ΔUV) that defines thecorrespondence relationship between the variable ΔUV and the emphasiscoefficient Coeff1, to calculate (determine) the emphasis coefficientCoeff1 in accordance with saturation of the pixel of interest.

In step S24, the saturation emphasis processing unit 71 multiplies theluminance signal Y of the pixel of interest by the calculated emphasiscoefficient Coeff1 to calculate the emphasized luminance signal Y′. Thecalculated luminance signal Y′ is supplied to the area emphasisprocessing unit 72 together with the U and V signals.

In step S25, it is determined whether the saturation emphasis processingunit 71 has set all the pixels of the image supplied from the imagequality adjustment processing unit 41 as pixels of interest.

In a case where it is determined in step S25 that the saturationemphasis processing unit 71 has not set all the pixels as pixels ofinterest, the processing returns to step S21. With this arrangement, theprocessing in steps S21 to S25 described above is repeated. In otherwords, a predetermined pixel not yet set as a pixel of interest is setas a pixel of interest, the emphasis coefficient Coeff1 in accordancewith saturation of the pixel of interest is calculated, and theluminance signal Y′ emphasized by the emphasis coefficient Coeff1 iscalculated.

On the other hand, in a case where it is determined in step S25 that allthe pixels have been set as pixels of interest, the saturation emphasisprocessing in FIG. 19 ends.

FIG. 20 is a flowchart for describing details of the saturation emphasisprocessing in step S1, and is a flowchart of the saturation emphasisprocessing in a case where the emphasis coefficient Coeff1 is calculatedon the basis of R, G, and B values of a pixel.

In the flowchart in FIG. 20 , first, in step S41, the saturationemphasis processing unit 71 sets a predetermined pixel of the imagesupplied from the image quality adjustment processing unit 41 as a pixelof interest.

In step S42, the saturation emphasis processing unit 71 converts animage signal in the YUV format of the pixel of interest into an imagesignal in the RGB format (R, G, and B signals).

In step S43, the saturation emphasis processing unit 71 calculates Rnrm,Gnrm, and Bnrm by normalizing the R, G, and B signals of the pixel ofinterest with maxRGB, which is the maximum value among the values thatthe R, G, and B signals may have.

In step S44, the saturation emphasis processing unit 71 calculates amargin Mg by using Rnrm, Gnrm, and Bnrm, which are the normalized R, B,and G signals of the pixel of interest. In other words, the saturationemphasis processing unit 71 calculates the margin Mg by multiplyingRnrm, Gnrm, and Bnrm by the power coefficients Cr, Cg, and Cb for R, G,and B respectively, and then subtracting the obtained values from 1.

In step S45, the saturation emphasis processing unit 71 calculates(determines) the emphasis coefficient Coeff1 in accordance withsaturation of the pixel of interest by substituting the calculatedmargin Mg into the function ƒ(Mg) that defines the correspondencerelationship between the margin Mg and the emphasis coefficient Coeff1.Then, the saturation emphasis processing unit 71 multiplies theluminance signal Y of the pixel of interest by the calculated emphasiscoefficient Coeff1 to calculate the emphasized luminance signal Y′. Thecalculated luminance signal Y′ is supplied to the area emphasisprocessing unit 72 together with the U and V signals.

In step S46, it is determined whether the saturation emphasis processingunit 71 has set all the pixels of the image supplied from the imagequality adjustment processing unit 41 as pixels of interest.

In a case where it is determined in step S46 that the saturationemphasis processing unit 71 has not set all the pixels as pixels ofinterest, the processing returns to step S41. With this arrangement, theprocessing in steps S41 to S46 described above is repeated. In otherwords, a predetermined pixel not yet set as a pixel of interest is setas a pixel of interest, the emphasis coefficient Coeff1 in accordancewith saturation of the pixel of interest is calculated, and theluminance signal Y′ emphasized by the emphasis coefficient Coeff1 iscalculated.

On the other hand, in a case where it is determined in step S46 that allthe pixels have been set as pixels of interest, the saturation emphasisprocessing in FIG. 20 ends.

Note that as described above, whether to execute, as the saturationemphasis processing in step S1, the emphasis processing based on the Uand V values described with reference to FIG. 19 or the emphasisprocessing based on the R, G, and B values described with reference toFIG. 20 can be optionally selected on the basis of setting informationor the like.

FIG. 21 is a flowchart for describing details of the area emphasisprocessing in step S2.

In the flowchart in FIG. 21 , first, in step S61, the area emphasisprocessing unit 72 divides an image supplied from the image qualityadjustment processing unit 41 into a plurality of areas. The number ofareas to be divided (division number) is determined in advance on thebasis of setting information or the like.

In step S62, the area emphasis processing unit 72 sets a predeterminedarea among the plurality of divided areas as an area of interest.

In step S63, the area emphasis processing unit 72 calculates the totallaser power value Area_(avgTTL) in the 3×3 neighboring areas centered onthe set area of interest (hereinafter referred to as “in and around thearea of interest” as appropriate). Note that as described above, thearea for calculating the total laser power value Area_(avgTTL) isdetermined in relation to the size of a pupil of a human eye and is notlimited to the nine (3×3) areas.

In step S64, the area emphasis processing unit 72 determines whether thetotal laser power value Area_(avgTTL) in and around the area of interestis smaller than the threshold Th determined on the basis of the lasersafety standard.

In a case where it is determined in step S64 that the total laser powervalue Area_(avgTTL) in and around the area of interest is smaller thanthe threshold Th, the processing proceeds to step S65, and the areaemphasis processing unit 72 calculates (determines) the emphasiscoefficient Coeff2 in accordance with the accumulated power value in andaround the area of interest by substituting the calculated total laserpower value Area_(avgTTL) into the function g(Area_(avgTTL)) thatdefines the correspondence relationship between the total laser powervalue Area_(avgTTL) and the emphasis coefficient Coeff2 as illustratedin FIG. 16 .

In step S66, the area emphasis processing unit 72 multiplies theluminance signal Y′ of each pixel in the area of interest by thecalculated emphasis coefficient Coeff2 to calculate the emphasizedluminance signal Y″ of each pixel in the area of interest. Thecalculated luminance signal Y″ is supplied to the pixel signalconversion unit 42 together with the U and V signals.

On the other hand, in a case where it is determined in step S64 that thetotal laser power value Area_(avgTTL) in and around the area of interestis greater than or equal to the threshold Th, the processing proceeds tostep S67, and the area emphasis processing unit 72, without performingemphasis processing, outputs directly the luminance signal Y′ of eachpixel in the area of interest as the luminance signal Y″ to the pixelsignal conversion unit 42 together with the U and V signals.

After step S66 or S67, the area emphasis processing unit 72 determinesin step S68 whether every one of the plurality of divided areas has beenset as an area of interest.

In a case where it is determined in step S68 that the area emphasisprocessing unit 72 has not set all the areas as areas of interest, theprocessing returns to step S62. With this arrangement, the processing insteps S62 to S68 described above is repeated. In other words, apredetermined area not yet set as an area of interest is set as an areaof interest, the emphasis coefficient Coeff2 in accordance with thetotal laser power value Area_(avgTTL) of the area of interest iscalculated, and the luminance signal Y″ emphasized by the emphasiscoefficient Coeff2 is calculated.

On the other hand, in a case where it is determined in step S68 thatevery one of the plurality of divided areas has been set as an area ofinterest, the area emphasis processing in FIG. 21 ends.

As described above, in the projection apparatus 1, the emphasisprocessing unit 61 emphasizes the luminance signal Y of the imagesupplied from the image quality adjustment processing unit 41 by usingthe emphasis coefficient Coeff1 in accordance with the saturation of theimage, and further emphasizes the luminance signal Y by using theemphasis coefficient Coeff2 in accordance with the accumulated laserpower value for each area. With this arrangement, it is possible toimprove brightness of a projected image while satisfying the safetystandard for laser products.

A human eye has a characteristic called the Helmholtz-Kohlrausch effect,which causes the human eye to perceive a highly saturated image asbright when the human eye sees such an image. A laser light source, dueto its characteristics, can reproduce a wide range of colors, and has aneffect of causing a highly saturated image to be perceived as brighterthan a normal light source does. Moreover, the saturation emphasisprocessing unit 71 performs saturation emphasis processing to emphasizeluminance in accordance with saturation. This allows an image to beexpressed more brightly and vividly.

Furthermore, the area emphasis processing unit 72 performs area emphasisprocessing to analyze brightness of an image and emphasize the power ofemitting light for each part (area) of the image. This allows even adark image having a low accumulated power value to be expressed as abrighter image.

Note that although the emphasis processing unit 61 has a configurationthat includes both the saturation emphasis processing unit 71 and thearea emphasis processing unit 72, the configuration may include only oneof them. Even in a case where either the emphasis processing by thesaturation emphasis processing unit 71 or the emphasis processing by thearea emphasis processing unit 72 is performed, an effect of improvingbrightness of a projected image can be obtained.

<9. Other Configuration Examples of Projection Apparatus>

In the embodiment described above, emphasis processing is performed as apart of processing to be executed by the controller 21. Alternatively,the processing to be performed by the emphasis processing unit 61 may beperformed by an image processing apparatus disposed separately from thecontroller 21.

For example, the projection apparatus may have a configuration in whichan image signal processor (ISP) 90 is disposed separately from thecontroller 21 as illustrated in FIG. 22 , and the ISP 90 as an imageprocessing apparatus performs the emphasis processing to be performed bythe emphasis processing unit 61.

<10. Configuration Example of Computer>

Alternatively, the processing to be performed by the emphasis processingunit 61 may be executed by a general-purpose computer or the like as animage processing apparatus.

FIG. 23 illustrates a configuration example of a computer in a casewhere the processing to be performed by the emphasis processing unit 61is executed by a general-purpose computer or the like as an imageprocessing apparatus.

This computer has a built-in central processing unit (CPU) 101. The CPU101 is connected with an input/output interface 105 via a bus 104. Thebus 104 is connected with a read only memory (ROM) 102 and a randomaccess memory (RAM) 103.

The input/output interface 105 is connected with an input unit 106, anoutput unit 107, a storage unit 108, and a communication unit 109. Theinput unit 106 includes an input device such as a keyboard, a mouse, amicrophone, a touch panel, or an input terminal. The output unit 107includes a display, a speaker, an output terminal, or the like. Thestorage unit 108 includes a hard disk, a RAM disk, a non-volatilememory, or the like for storing programs and various data. Thecommunication unit 109 includes a local area network (LAN) adapter orthe like and executes communication processing via a network asrepresented by the Internet. Furthermore, the input/output interface 105is connected with a drive 110 for reading and writing data on aremovable medium 111 such as a magnetic disk, an optical disk, amagneto-optical disk, or a semiconductor memory.

The CPU 101 executes various types of processing in accordance with aprogram loaded from the storage unit 108 into the RAM 103. The RAM 103also stores, as appropriate, data or the like necessary for the CPU 101to execute various types of processing.

To perform the series of processing described above, the computerconfigured as described above causes the CPU 101 to, for example, load aprogram stored in the storage unit 108 into the RAM 103 via theinput/output interface 105 and the bus 104 and then execute the program.

The program to be executed by the computer (CPU 101) can be provided by,for example, being recorded on the removable medium 111 as a packagemedium or the like. Furthermore, the program can be provided via a wiredor wireless transmission medium such as a local area network, theInternet, or digital satellite broadcasting.

Inserting the removable medium 111 into the drive 110 allows thecomputer to install the program into the storage unit 108 via theinput/output interface 105. Furthermore, the program can be received bythe communication unit 109 via a wired or wireless transmission mediumand installed into the storage unit 108. In addition, the program can beinstalled in advance in the ROM 102 or the storage unit 108.

Note that the program to be executed by the computer may be a programthat performs the series of processing in chronological order asdescribed in the present specification, or may be a program thatperforms the series of processing in parallel or when needed, forexample, when the processing is called.

<11. Example of Application to Electronic Equipment as ProjectionModule>

Moreover, while the projection apparatus 1 is configured alone in theexample described above, the projection apparatus 1 may be, for example,designed as a projection module having about one chip and may beembedded in electronic equipment such as a mobile phone, a smartphone, amobile terminal, or an imaging device such as a digital still camera ora video camera so as to project an image stored in the electronicequipment or an image received through communication, for example.

FIG. 24 illustrates a configuration example of electronic equipmentincluding a projection module 151 including functions as the projectionapparatus 1 in FIG. 1 as a module in one chip. Here, the functions andconfigurations of a CPU 131 to a removable medium 141 are substantiallythe same as those of the CPU 101 to the removable medium 111, andtherefore the description thereof is omitted. Still, the CPU 131 to theremovable medium 141 of the electronic equipment in FIG. 24 aregenerally designed to be more compact and more portable than the CPU 101to the removable medium 111. Note that the projection module 151 has thesame function as that of the projection apparatus 1 in FIG. 1 , andtherefore the description thereof is omitted.

Embodiments of the present technology are not limited to the embodimentdescribed above but can be modified in various ways within a scope ofthe present technology.

The embodiment described above adopts a configuration in which theemphasis coefficient Coeff1 and the emphasis coefficient Coeff2 arecalculated by substituting predetermined values into the functionƒ(ΔUV), the function ƒ(Mg), and the function g(Area_(avgTTL)).Alternatively, the emphasis coefficient Coeff1 and the emphasiscoefficient Coeff2 may be determined (calculated) by holding a tablethat stores correspondence relationships similar to those defined by afunction ƒ( ) or a function g( ) and referring to the table.

For example, the present technology can have a cloud computingconfiguration in which a plurality of apparatuses shares one functionand collaborates in processing via a network.

Furthermore, each step described in the flowcharts described above canbe executed by one apparatus or can be shared by a plurality ofapparatuses.

Moreover, in a case where a plurality of types of processing is includedin one step, the plurality of types of processing included in that stepcan be executed by one apparatus or can be shared by a plurality ofapparatuses.

Note that the effects described in the present specification are merelyexamples and are not restrictive, and effects other than those describedin the present specification may be obtained.

Note that the present technology can also be configured as describedbelow.

(1)

An image processing apparatus including

a saturation emphasis processing unit that determines, in accordancewith saturation of an image, a first emphasis coefficient thatemphasizes luminance of the image, and converts a luminance signal ofthe image on the basis of the determined first emphasis coefficient.

(2)

The image processing apparatus according to (1), in which

the saturation emphasis processing unit determines the first emphasiscoefficient in accordance with an absolute value of a color-differencecomponent of each pixel of the image.

(3)

The image processing apparatus according to (2), in which

the saturation emphasis processing unit determines the first emphasiscoefficient by substituting either an absolute value of a Cr componentor an absolute value of a Cb component of each pixel, whichever islarger, into a first function.

(4)

The image processing apparatus according to (3), in which

in the first function, the first emphasis coefficient increases as avalue substituted into the first function is closer to 0.5.

(5)

The image processing apparatus according to (1), in which

the saturation emphasis processing unit determines the first emphasiscoefficient in accordance with R, G, and B values of each pixel of theimage.

(6)

The image processing apparatus according to (5), in which

the saturation emphasis processing unit normalizes the R, G, and Bvalues of each pixel of the image, and determines the first emphasiscoefficient on the basis of results of multiplying the normalized R, G,and B values by ratios of R, G, and B respectively.

(7)

The image processing apparatus according to (6), in which

the saturation emphasis processing unit determines the first emphasiscoefficient by substituting, into a first function, a value computed byusing the results of multiplying the normalized R, G, and B values bythe ratios of R, G, and B respectively.

(8)

The image processing apparatus according to (7), in which

in the first function, the first emphasis coefficient increases as thecomputed value increases.

(9)

The image processing apparatus according to any one of (1) to (8),further including

an area emphasis processing unit that divides the image into a pluralityof areas, determines for each of the areas a second emphasis coefficientthat emphasizes luminance of the image, and converts a luminance signalof the image on the basis of the determined second emphasis coefficient.

(10)

The image processing apparatus according to (9), in which

the area emphasis processing unit determines the second emphasiscoefficient of an area of interest, which is a target area among theplurality of areas, by calculating a total power value in areas withinand neighboring the area of interest and, in a case where the totalpower value is smaller than a predetermined threshold, substituting thetotal power value into a second function.

(11)

The image processing apparatus according to (9) or (10), in which

a size of each of the areas is smaller than a size of a pupil of a humaneye, and

a combined size of areas within and neighboring the area of interest,which is a size of an area for calculating the total power value, islarger than the size of a pupil of a human eye.

(12)

An image processing method including:

determining, by an image processing apparatus, an emphasis coefficientthat emphasizes luminance of an image in accordance with saturation ofthe image; and

converting, by the image processing apparatus, a luminance signal of theimage on the basis of the determined emphasis coefficient.

(13)

A projection apparatus including:

a saturation emphasis processing unit that determines, in accordancewith saturation of an input image, an emphasis coefficient thatemphasizes luminance of the image, and converts a luminance signal ofthe image on the basis of the determined emphasis coefficient;

a laser light source unit that outputs a laser beam in accordance with apixel signal of the image obtained by converting the luminance signal;and

a scanning unit that reflects the laser beam and performs scanning withthe laser beam in a horizontal direction and a vertical direction.

REFERENCE SIGNS LIST

-   -   1 Projection apparatus    -   2 a Projection image    -   21 Controller    -   22 Laser driver    -   23 Mirror driver    -   24R, 24G, 24B Laser light source unit    -   27 Drive mirror    -   61 Emphasis processing unit    -   71 Saturation emphasis processing unit    -   72 Area emphasis processing unit    -   90 ISP    -   101 CPU    -   102 ROM    -   103 RAM    -   106 Input unit    -   107 Output unit    -   108 Storage unit    -   109 Communication unit    -   110 Drive    -   151 Projection module

The invention claimed is:
 1. An image processing apparatus, comprising:a saturation emphasis processing unit configured to: determine, for afirst function, a specific value that is larger among an absolute valueof a Cr component and an absolute value of a Cb component of each pixelof an image; determine a first emphasis coefficient that emphasizesluminance of the image, wherein the first emphasis coefficient isdetermined based on saturation of the image and substitution of thespecific value into the first function; and convert a first luminancesignal of the image based on the determined first emphasis coefficient.2. The image processing apparatus according to claim 1, wherein in thefirst function, the first emphasis coefficient increases as the specificvalue substituted into the first function is closer to 0.5.
 3. The imageprocessing apparatus according to claim 1, wherein the saturationemphasis processing unit is further configured to determine the firstemphasis coefficient based on R, G, and B values of each pixel of theimage.
 4. The image processing apparatus according to claim 3, whereinthe saturation emphasis processing unit is further configured to:normalize the R, G, and B values of each pixel of the image; anddetermine the first emphasis coefficient based on results ofmultiplication of the normalized R, G, and B values by ratios of R, G,and B respectively.
 5. The image processing apparatus according to claim4, wherein the saturation emphasis processing unit is further configuredto determine the first emphasis coefficient based on substitution of avalue into a second function, and the value substituted into the secondfunction is based on the results of multiplication of the normalized R,G, and B values by the ratios of R, G, and B respectively.
 6. The imageprocessing apparatus according to claim 5, wherein in the secondfunction, the first emphasis coefficient increases as the valuesubstituted in the second function increases.
 7. The image processingapparatus according to claim 1, further comprising an area emphasisprocessing unit configured to: divide the image into a plurality ofareas; determine, for each of the plurality of areas, a second emphasiscoefficient that emphasizes luminance of the image; and convert a secondluminance signal of the image based on the determined second emphasiscoefficient.
 8. The image processing apparatus according to claim 7,wherein the area emphasis processing unit is further configured to:calculate a total power value in areas within and neighboring an area ofinterest which is a target area among the plurality of areas; determinethe second emphasis coefficient of the area of interest; and substitutethe total power value into a second function in a case where the totalpower value is smaller than a threshold power value.
 9. The imageprocessing apparatus according to claim 8, wherein a size of each of theplurality of areas is smaller than a size of a pupil of a human eye, anda combined size of the areas within and neighboring the area ofinterest, which is a size of an area to calculate the total power value,is larger than the size of the pupil of the human eye.
 10. An imageprocessing method, comprising: determining, by an image processingapparatus, a specific value that is larger among an absolute value of aCr component and an absolute value of a Cb component of each pixel of animage, for a function; determining, by the image processing apparatus,an emphasis coefficient that emphasizes luminance of the image, whereinthe emphasis coefficient is determined based on saturation of the imageand substitution of the specific value into the function; andconverting, by the image processing apparatus, a luminance signal of theimage based on the determined emphasis coefficient.
 11. A projectionapparatus, comprising: a saturation emphasis processing unit configuredto: determine, for a function, a specific value that is larger among anabsolute value of a Cr component and an absolute value of a Cb componentof each pixel of an image; determine an emphasis coefficient thatemphasizes luminance of the image wherein the emphasis coefficient isdetermined based on saturation of the image and substitution of thespecific value into the function; and convert a luminance signal of theimage based on the determined emphasis coefficient; a laser light sourceunit configured to output a laser beam based on a pixel signal of theimage obtained by conversion of the luminance signal; and a scanningunit configured to: reflect the laser beam; and execute a scanningprocess with the laser beam in a horizontal direction and a verticaldirection.
 12. An image processing apparatus, comprising: a saturationemphasis processing unit configured to: normalize R, G, and B values ofeach pixel of an image; determine, based on saturation of the image andresults of multiplication of the normalized R, G, and B values by ratiosof R, G, and B respectively, an emphasis coefficient that emphasizesluminance of the image; and convert a luminance signal of the imagebased on the determined emphasis coefficient.
 13. An image processingapparatus, comprising: a saturation emphasis processing unit configuredto: determine, based on saturation of an image, a first emphasiscoefficient that emphasizes luminance of the image; and convert a firstluminance signal of the image based on the determined first emphasiscoefficient; and an area emphasis processing unit configured to: dividethe image into a plurality of areas; calculate a total power value inareas within and neighboring an area of interest which is a target areaamong the plurality of areas; substitute the total power value into afunction in a case where the total power value is smaller than athreshold power value; determine, for the area of interest, a secondemphasis coefficient that emphasizes the luminance of the image, whereinthe second emphasis coefficient is determined based on the substitutionof the total power value into the function; and convert a secondluminance signal of the image based on the determined second emphasiscoefficient.